1. Technical Field
The disclosure generally relates to a light-emitting panel, and particularly to a light-emitting panel incorporating light-emitting diodes as light source.
2. Description of Related Art
Light-emitting panels are commonly used in luminous signs for advertising purposes. Light of the typical light-emitting panels is provided by a tubular low-pressure mercury-vapor discharge lamp, for example a cold cathode fluorescent lamp (CCFL). However, CCFL is harmful to the environment.
Light emitting diodes (LEDs) have many advantages, such as high luminance, low power consumption, highly compatible with integrated circuits, long-term reliability and environmental friendliness and are widely used as light sources instead of CCFLs, as described in an article entitled “Solid-State Lighting: Toward Superior Illumination” cited in a publication of Proceedings of the IEEE, Vol. 93, No. 10, October, 2005 authored by Michael S. Shur.
U.S. Pat. No. 6,539,656 discloses a light-emitting panel with LEDs. The light-emitting panel includes a light-emitting window and an opposite rear wall. The rear wall has two opposed edge surfaces. At least one of the edge surfaces is light transmitting and associated with a plurality of LEDs. A plurality of deformities is provided in the rear wall for extracting light from the panel via the light emitting window. However, the deformities can only be arranged horizontally or vertically, and the light-emitting panel can only display two different light symbols. As a result, the attractiveness of the light-emitting panel is limited.
Therefore, a light-emitting panel is desired to overcome the above shortcomings.